Invest in a Refractometer...

[Reeferhead]

... or at least calibrate your hydrometer with a friends refractometer regularly.

Up until about 6 weeks ago I was running old school with the same hydrometer I had been using since 2000. I have never calibrated it and never assumed it to be off by much. I figured if my Specific Gravity was off by 0.002 or so in either direction, who cares, as long as its stable right?

Well, I bought a refractometer about six weeks back, really out of a once a month desire to have new "cool guy stuff." After calibrating the refractometer to a known concentration, I checked my tank water... 1.033!

Over a span of about 3 weeks I've brought my SG back down to 1.025 and my tank has never looked better. I never really noticed any serious issues will the SG so high but I've noticed the color of many of my corals color has improved since I've brought it back down. My frogsspawn and crocea clam which all paled out when I introduced them months back, now finally have the rich colors they had when I first put them in. Also, I'm seeing new polyps on some of my zoanthids that haven't grown in probably close to a year, and I could never figure out why. Finally, most likely unrelated, but yet a strange coincidence, the Lobophora algae I've been futilely battling for over a year is finally starting to recede!

I knew hydrometers could be inaccurate but I never guessed they could be that far off. I figure the one I have started out fine but slowly degraded over time and became less and less accurate. Its odd how one could be in this hobby for so long and over look something so basic . This is just a little advice to save someone the same mistake I made. If you have a hydrometer and want to check it against a refractometer shoot me a PM.

Later,

[Nanook]

Great advice!! I have never trusted a hydrometer since I took the advice of the guys/gals here on RC a long time ago.

[Reeferhead]

I forgot to add,

You can also calibrate your hydrometer with a known concentration. You can use distilled water if your hydrometer will register 1.000. However, it won't be as accurate as if you use something closer to 1.025

[DrBDC]

If you order the pinpoint salinity monitor calibration fluid and calibrate your refractometer with it at exactly 35/1.0265 you'll be much more accurate.

[Reeferhead]

Originally posted by DrBDC
If you order the pinpoint salinity monitor calibration fluid and calibrate your refractometer with it at exactly 35/1.0265 you'll be much more accurate.

I did... that was my known concentration. I would have mentioned but couldn't remember the name of the brand.

[DrBDC]

[paulamrein]

How often should you re-calibrate your refractometer? It was calibrated at the store when I bought it, since than I have just ran with it. Does it lose accuracy after a while?

[StupidsReef]

I re-calibrate mine before each use. And before and after I loan it out to IM LON2 & Rich1972. Mine rarely really needs to be re-calibrated, But if a spash of liquid touches it and then I try to use it, it would be off. And beings everyone know's how I'm NOT such a cluts and DON'T ever make a mess......I think it's best to take the 4 seconds it takes to re-calibrated the darn thing before I use it.

[Reeferhead]

I've been recalibrating mine fairly often, about every 2 or 3 uses, because I just got it. Even though its supposed to be temperature compensating, I've noticed that is off a little when I use it downstairs (where my water change water is) as a opposed to upstairs by the tank. Its about 10 degrees cooler downstairs. I have this one:

Premium Blue Refractometer - RHS-10ATC

[StupidsReef]

I bought mine from MS, about 2 years ago I guess. All my water in located in the fish room I've never had that issue. But as long as your aware of it, then you know how to correct it so I would say that's not really and issue. That looks like a nice one though, I like the blue color mines dead black just plain 'ol ugly.